May 21, 2003

Products Affected

Problem Description

The following two problems associated with ping were identified in Cisco caveat CSCuk42211 and may occur on Cisco 7200, 7500, or 12000 Routers running Cisco IOS Software Release 12.0(25)S:

On a point-to-point interface (serial, Packet-over-Sonet, PPP), an interface may not be able to properly trace its own IP address. Tracing its own serial (or other point-to-point address) IP address will not display the peer address any more.

On an interface in loopback, self-ping may fail. If it succeeds, the Rx LED may not flash to indicate successful packet receipt.

Background

The self-ping and traceroute failures indicated by this field notice do not affect all Cisco 7200, 7500, or 12000 line cards, and will not affect any line card's ability to pass traffic.

Traceroute symptoms are limited to an interface being able to properly trace its own IP address for test purposes.

With the topology UUT-(x.x.x.x)----serial----(x.x.x.y)-peer, where UUT sends a trace to x.x.x.x (itself), the expected behavior is shown below.

Problem Symptoms

Self-ping on an interface in loopback can demonstrate the following problems:

The ping succeeds, but the Rx LED does not flash to indicate successful packet receipt.

The ping fails, as reported by on the console.

On a very limited number of line cards, only the local router and not next-hop routers will be listed after the traceroute command has been issued.

Workaround/Solution

This is a cosmetic problem that does not effect live traffic nor are these problems any indication of hardware failures.

The following mechanisms can be used as a workaround to verify a working interface and good hardware:

The interface of a line card or port adapter is fine when the interface is in service, is connected to another interface, and you can ping the other interface.

If the interface of a line card or port adapter is not in service, loop the interface either physically (with a fiber cable) or enter the loopback interface configuration command; when the state of the interface is "up," the hardware is fine.

DDTS

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